Leptogenys kraepelini Forel, 1905

Hamer, Matthew T., Lee, Jonathan Hon Chung, Tse, Cheung Yau Leo, Silva, Thiago S. R. & Guénard, Benoit, 2024, The Leptogenys Roger, 1861 (Formicidae, Ponerinae) of Hong Kong SAR with additional records from Guangdong, China, ZooKeys 1202, pp. 169-211 : 169-211

Leptogenys kraepelini Forel, 1905

Figs 2 B , 6 A , 15 , 21 A new record

Leptogenys (Lobopelta) kraepelini Forel, 1905 f: 5 (w.) Indonesia (Java).

Leptogenys kraepelini baccha [senior synonym] Santschi, 1919: 336 (w.) Vietnam: Xu and He 2015: 142.

Measurements.

Workers (n = 15): HL 1.68 – 1.86; HLL 1.32 – 1.51; HLA 0.33 – 0.38; HW 1.09 – 1.23; CML 0.35 – 0.43; SL 1.7 – 2.04; AII 0.25 – 0.31; AFI 0.4 – 0.5; AFII 0.33 – 0.39; EL 0.41 – 0.47; ML 0.78 – 0.87; PrL 1.03 – 1.22; PrH 0.63 – 0.93; PrW 0.97 – 1.11; WL 2.91 – 3.26; PeL 0.92 – 1.07; PeH 0.87 – 0.99; PeW 0.35 – 0.65; DPL 0.9 – 1.02; CI 62.84 – 67.07; CLI 20.97 – 24.54; SI 153.66 – 174.8; OI 29.39 – 33.12; LPI 89.2 – 318.31; DPI 39.4 – 67.12.

Ergatoid queen (n = 1): HL 1.63; HLL 1.29; HLA 0.36; HW 1.67; CML 0.4; SL 1.53; AII 0.22; AFI 0.35; AFII 0.29; EL 0.42; ML 0.84; PrL 1.05; PrH 0.79; PrW 0.99; WL 2.71; PeL 0.73; PeH 0.84; PeW 0.55; DPL 0.71; CI 102.52; CLI 24.25; SI 91.8; OI 32.87; LPI 114.93; DPI 77.75.

Morphological variation.

Specimens collected in Hong Kong match well with the description provided by Forel, 1905 of L. kraepelini . However, the sculpture on the propodeum (as ‘ sloping surface of the metanotum’ in Forel 1905) is not entirely ‘ smooth’ ( Forel 1905), but instead with transverse striations of varying degrees of pronunciation from few to many striae. Xu and He (2015) utilised this character (among others) to differentiate L. kraepelini from L. chinensis (Mayr, 1870) , L. chinensis having transverse striation and L. kraepelini lacking it. Such striations appear absent in the dorsal image of the L. kraepelini ( CASENT 0281936, antweb. org) studied by Xu and He (2015). However, this specimen (from West Java) could represent a morphological extreme for this character. With a large distribution across Southeast Asia, this species likely shows a high degree of morphological variability similar to L. diminuta and L. kitteli . We suggest that this character should be treated with caution until the holotype specimen and additional material of L. kraepelini can be more closely scrutinised. Within Hong Kong, morphological variation appears to be limited. Most variation is associated with colour, with workers varying from reddish brown to jet-black, to black with a blue iridescent shine. The possibility of cryptic species within L. kraepelini and L. chinensis requires further taxonomic investigation which is not within the scope of this study. As such, despite ergatoids presented here we refrain from describing them.

Comparative notes.

This species highly resembles L. peuqueti and L. grohli within Hong Kong. However, L. kraepelini can be separated from both species by its much larger size, the distinctly posteriorly projecting propodeal lobes and the truncated anterior clypeal margin. Leptogenys kraepelini has been confused with L. chinensis in the past ( Xu and He 2015). However, L. kraepelini has a rectangular head that does not significantly narrow behind the eyes as in L. chinensis ; has punctuate sculpture between the clypeus and eyes which L. chinensis lacks, and a straight anterolateral clypeal margin which is sinuate in L. chinensis . More differing characters will likely be revealed upon closer inspection of type material and the examination of more specimens from across the wider region. Specimens previous determined to be L. chinensis from Guangdong were not examined in this study ( Wu et al. 2008; Zhao et al. 2009). Such specimens should be re-examined, especially considering L. kraepelini is now confirmed from Guangdong and Hong Kong (this study), as well as the previously known misidentifications of L. chinensis for L. kraepelini (and L. peuqueti ) in the past.

Distribution.

Leptogenys kraepelini is widely distributed across Indomalaya, recorded from China (Yunnan and Hong Kong SAR), Vietnam, Laos, Thailand, Malaysia Peninsula, Singapore, Borneo, Sumatra, and Java ( Bakhtiar and Chiang 2010; Xu and He 2015; Janicki et al. 2016; Guénard et al. 2017; Khachonpisitsak et al. 2020; Wang et al. 2022). This species is currently absent from many southern Chinese provinces which likely reflects sampling effort in these regions, or has been incorrectly identified as L. chinensis .

Ecology.

This species is known to nest within rotting wood in young to old growth secondary and shrublands but is seemingly absent from highly disturbed environments. Specimens have been collected either individually or in small groups (three individuals) during the day, with colonies reproducing through ergatoid queens ( Ito 1997). Leptogenys kraepelini appears to have a specialised diet on earwigs ( Steghaus-Kovac and Maschwitz 1993) but has been observed preying upon termites in Hong Kong ( CYLT pers. obs.).

Material examined.

Workers (n = 38): China • 1 worker; Hong Kong SAR, The Peak ; 13 Jul. 1992; J. R. Fellowes leg.; HKBM MBS 006905 . • 1 worker; Hong Kong SAR, Hong Kong Island, The Peak ; 24 Sep. 1993; J. R. Fellowes leg.; HKBM MBS 015288 . • 1 worker; Hong Kong SAR, The Peak ; 27 Sep. 1994; J. R. Fellowes leg.; HKBM MBS 006660 . • 1 worker; Guangdong Prov. Daw U Ling ; 28 Apr. 1997; J. R. Fellowes leg.; HKBM MBS 015287 • 1 worker; Hong Kong SAR, Victoria Park ; 27 Jun. 1999; SK. Yamane leg.; SKYC MBS 006658 , MBS 006659 . • 1 worker; Hong Kong SAR, Shing Mun Reservoir ; 22.39737, 114.15268; 230 m a. s. l.; 6 Jul. 2011; P. S. Ward leg.; Secondary forest, ex. decay wood; IBBL ANTWEB 1010182 . • 1 worker; Hong Kong SAR, Shing Mun ; 22.39693, 114.153; 240 m a. s. l.; 14 May. 2015; R. H. Lee leg.; Feng Shui Forest, Pitfall trap; IBBL RHL 00364 , RHL 00367 , RHL 00392 , RHL 00407 . • 1 worker; Hong Kong SAR, Sunset Peak ; 22.266, 113.953; 430 m a. s. l.; 3 Jun. 2015; R. H. Lee leg.; Secondary forest, Pitfall trap; IBBL RHL 00928 . • 1 worker; Hong Kong SAR, Aberdeen Reservoir ; 22.259, 114.16; 170 m a. s. l.; 26 Jun. 2015; R. H. Lee leg.; Secondary forest, Pitfall trap; IBBL RHL 00861 . • 1 worker; Hong Kong SAR, Aberdeen Reservoir ; 22.262, 114.16; 180 m a. s. l.; 26 Jun. 2015; R. H. Lee leg.; Secondary forest, Pitfall trap; IBBL RHL 01297 . • 1 worker; Hong Kong SAR, The Peak ; 22.277, 114.143; 450 m a. s. l.; 17 Aug. 2015; R. H. Lee leg.; Secondary forest, Pitfall trap; IBBL RHL 02628 . • 1 worker; Hong Kong SAR, Kap Lung ; 22.41666, 114.10222; 256 m a. s. l.; 19 Sep. 2015; T. Tsang leg.; Winkler leaf litter Ex; IBBL TT 01228 . • 1 worker; Hong Kong SAR, Tai Tam ; 22.396, 114.093; 420 m a. s. l.; 26 Oct. 2015; R. H. Lee leg.; Bamboo, Pitfall trap; IBBL RHL 02778 . • 1 worker; Hong Kong SAR, Shing Mun ; 22.39693, 114.153; 240 m a. s. l.; 17 May. 2016; R. H. Lee leg.; Feng Shui Forest, Winkler leaf litter Ex; IBBL RHL 03204 . • 1 worker; Hong Kong SAR, Lung Fu Shan ; 22.27603, 114.14199; 400 m a. s. l.; 11 Jul. 2016; R. H. Lee leg.; Secondary forest, Winkler leaf litter Ex; IBBL RHL-SIA- 89 . • 1 worker; Hong Kong SAR, Tai Lam Country Park ; 22.37598, 114.04713; 200 m a. s. l.; 3 Nov. 2017; R. Cheung & M. Pierce leg.; Winkler leaf litter Ex; HKBM MBS 011437 . • 1 worker; Hong Kong SAR, Wong Lung Hang ; 22.2668, 113.9524; 400 m a. s. l.; 11 May. 2023; M. T. Hamer leg.; Young secondary forest, Hand collection; IBBL ANTWEB 101020 . • 1 worker; Hong Kong SAR, Lantau; A Po Long ; 22.28186, 113.9835; 200 m a. s. l.; 5 Jun. 2023; M. T. Hamer leg.; Young secondary forest, Hand collection; IBBL ANTWEB 1010131 , ANTWEB 1010132 , ANTWEB 1010176 . • 1 worker; Hong Kong SAR, Sunset Peak , Wong Lung Hang path; 22.2602, 113.95906; 650 m a. s. l.; 7 Jul. 2023; M. T. Hamer leg.; Montane forest, Hand collection; IBBL ANTWEB 1010121 . • 5 workers; Hong Kong SAR, Tai Mo Shan ; 22.40585, 114.1063; 517 m a. s. l.; 26 Aug. 2023; M. T. Hamer leg.; Secondary forest, ex. Decay wood; IBBL MTH 70 , MTH 157 . • 1 worker; Hong Kong SAR, Tai Mo Shan ; 22.40403, 114.10691; 471 m a. s. l.; 3 Sep. 2023; M. T. Hamer leg.; Secondary forest, Nest ex. decay log; IBBL ANTWEB 1010169 , ANTWEB 1010174 . • 1 worker; Hong Kong SAR, Tai Mo Shan ; Kap Lung Forest Trail ; 22.41088, 114.10451; 450 m a. s. l.; 3 Sep. 2023; M. T. Hamer leg.; Secondary forest, ex. decaying log; IBBL MTH 276 . • 1 worker; Hong Kong SAR, Severn Road ; 22.27044, 114.15621; 380 m a. s. l.; 5 Sep. 2023; C. Y. L. Tse leg.; Nest ex.; IBBL ANTWEB 1010168 , ANTWEB 1010175 . • 4 workers; Hong Kong SAR, Wong Lung Hang ; 22.26964, 113.95248; 265 m a. s. l.; 5 Sep. 2023; M. T. Hamer leg.; Secondary forest, ex. decaying log; IBBL MTH 308 , MTH 323 , MTH 335 , MTH 336 .

Ergatoids (n = 2): China • 1 ergatoid; Hong Kong SAR, Tai Mo Shan ; Kap Lung Forest Trail ; 22.41088, 114.10451; 450 m a. s. l.; 3 Sep. 2023; M. T. Hamer leg.; Secondary forest, nest ex. decaying log; IBBL MTH 276 . • 1 ergatoid; Hong Kong SAR, Severn Road ; 22.27044, 114.15621; 380 m a. s. l.; 5 Sep. 2023; C. Y. L. Tse leg.;, Nest ex.; IBBL ANTWEB 1010172 .

Figures

Figure 2. Differing anterior clypeal shapes A Leptogenys rufida (RHL 1259) B L. kraepelini (ANTWEB 1010120).

Figure 6. Contrasting petiole shapes between L. kraepelini and L. diminuta A L. kraepelini (ANTWEB 1010121) B L. diminuta (ANTWEB 1010183).

Figure 15. Leptogenys kraepelini (RHL 00392) and ergatoid (ANTWEB 1010172) A worker in lateral view B worker in dorsal view C worker in head in full face view D ergatoid in lateral view E ergatoid in lateral view and F ergatoid in dorsal view.

Figure 21. Further distribution maps of Leptogenys species recorded from Hong Kong A L. kraepelini B L. laeviterga C L. peuqueti D L. rufida E L. strena. The base map displayed shows tree canopy cover with the darker green areas indicating greater tree cover.